Doctors are urging children and adults to wear protective goggles when playing with Nerf guns, as the foam darts have been found to cause serious eye injuries.

Accident and emergency medics from Moorfields Eye Hospital in London say they have treated three people with pain, blurred vision and internal bleeding as a result of being hit.

Writing in British Medical Journal (BMJ), authors Mukhtar Bizrah and Seema Verma, said: “Sports in which the risk of [eye] trauma is relatively high, such as squash ball, have seen an introduction of protective eyewear in the UK.

“This case series emphasises the seriousness of [eye] injury from Nerf gun projectiles and calls into consideration the need for protective eyewear with their use.”

Nerf toys, which are manufactured by Hasbro, include a range of guns, blasters and bows aimed at children aged eight and over.

The company also sells replacement bullets or darts but cheaper versions are available online from other retailers. Doctors have warned that the bullets are harder and could potentially cause more damage, which parents may not realise.

They have also warned that children are increasingly watching YouTube videos advising them on how to make the toys more powerful.

In the report, doctors describe the injuries of two adults and a child in separate incidents linked to Nerf guns.

One 32-year-old man was shot in the eye from eight metres away by a child with a Nerf gun, and suffered blurred vision and a red eye.

A 43-year-old woman was shot in her right eye from a distance of one metre and complained of blurred vision and a red, sore eye.

An 11-year-old child also suffered a shot in his right eye from a distance of two metres, and complained of pain and blurred vision.

In each case their sight returned, but the doctors said the guns had the potential to cause long-term vision loss.

A spokesman for Hasbro said: “Product safety is of utmost concern at Hasbro. Nerf products are designed based on years of consumer insights and research, and undergo rigorous reviews and testing to assure that they are safe and fun to play with, and meet or exceed global standards and regulations.

“Nerf foam darts and foam rounds are not hazardous when used properly. Consumers must never aim Nerf blasters at a person’s eyes or face, should only use the foam darts and foam rounds designed for specific Nerf blasters, and never modify darts or blasters. There are darts available to buy claiming to be Nerf compatible, however these darts are not Nerf-branded and may not meet safety standards and regulations.

“Most of our Nerf product line is age graded 8+, but we encourage parents and caregivers to read the packaging because some blasters are graded for older consumers.

“It’s important to note that the Nerf brand encourages parents and caregivers to be involved in aspects of their children’s development, including play. Ultimately, a parent or caregiver knows his or her child best and is best equipped to make decisions on what forms of play and entertainment are most appropriate for his or her child.”